1. Field of the Invention
The invention relates to dry spinning spandex yarns and, more particularly, it relates to a rectangular spinning cell for dry spinning spandex.
2. Description of the Background Art
One method of making spandex is to dry-spin it from a solvent which is evaporated from the threadline by a hot, inert gas. As disclosed in U.S. Pat. Nos. 3,737,508, 4,431,602, 4,679,998 and 4,804,511, this method generally employs an upright heated tube (spin cell), spinnerets at the top end of the tube through which the solution is introduced into the spin cell, a hot inert gas which evaporates the solvent as it contacts the threadlines in the tube, and removal of the spandex filaments from the bottom of the spin cell.
Research Disclosure No. 34866, April 1993, describes a variety of apparatus configurations for dry-spinning synthetic fibers including spandex. FIGS. 10a through 10f depict different spinneret hole arrangements including circular and uniform linear capillary arrays. FIGS. 1 through 9 depict different capillary arrangements for introducing the gas into the cell.
James et al., U.S. Pat. No. 5,387,387, disclose advantages of a uniform, linear array of spinneret capillary groups over a circular arrangement for dry spinning spandex. In this method, a hot, inert gas is distributed about the spinnerets and flows down the spin cell cocurrently with the threadlines. The spinnerets can be arranged in one row or more than one row and each row can be staggered within each linear configuration as illustrated in FIGS. 2 and 3 of the '387 patent. However, with cocurrent feed of the hot, inert gas, the gas penetration into the filament bundles is poor, and solvent is not effectively removed from the filament bundles. Such deficiencies produce filaments having non-uniform physical properties such as tenacity and load power. The filaments closer to the gas feed have properties which differ from those of the filaments further from the gas feed.
The highly regular, uniform arrangements disclosed in the prior art make spandex which is unsatisfactorily nonuniform along its length, and a practical arrangement is still desired.